Various instruments and systems have been proposed for assessing a person's ability to move rapidly in one direction in response to either planned or random visual or audio cuing. One such system is disclosed in French et. al. U.S. Ser. No. 07/984,337 , filed on Dec. 2, 1992, entitled "Interactive Video Testing and Training System," and assigned to the assignee of the present invention. Therein, a floor is provided with a plurality of discretely positioned force measuring platforms. A computer controlled video monitor displays a replica of the floor and audibly and visually prompts the user to move between platforms in a pseudo-random manner. The system assesses various performance parameters related to the user's movements by measuring critical changes in loading associated with reaction time, transit time, stability time and others. At the end of the protocol, the user is provided with information related to weight-bearing capabilities including a bilateral comparison of left-right, forward-backward movement skills. Such a system provides valuable insight into user's movement abilities in a motivating, interactive environment.
Sensing islands or intercept positions in the form of digital switches or analog sensors that respond to hand or foot contact when the player arrives at a designated location have been proposed for providing a variety of movement paths for the user as disclosed in U.S. Pat. No. 4,627,620 to Yang. The measurement of transit speeds has also been proposed using discrete optical light paths which are broken at the designated locations as disclosed in U.S. Pat. No. 4,645,458 to Williams. However the inability to track the player's movement path continuously inhibits the development of truly interactive games and simulations. In these configurations, the actual position of the player between positions is unknown inasmuch as only the start and finish positions are determined. Most importantly, the requirement that the player move to designated locations is artificial and detracts from actual game simulation in that an athlete rarely undertakes such action, rather the athlete moves to a visually determined interception path for the particular sports purpose.
For valid testing of sports specific skills, many experts consider that, in addition to unplanned cuing, it is important that the distances and directions traveled by the player be representative of actual game play. It is thus desirable to have the capability to measure transit speeds over varying vector distances and directions such that the results can be of significant value to the coach, athletic trainer, athlete and clinician. It is also important to detect bilateral asymmetries in movement and agility so as to enable a clinician or coach to develop and assess the value of remedial training or rehabilitation programs. For example, a rehabilitating tennis player may move less effectively to the right than to the left due to a left knee injury, i.e. the "push off" leg. A quantitative awareness of this deficiency would assist the player in developing compensating playing strategies, as well as the clinician in developing an effective rehabilitation program.
In actual competition, a player does not move to a fixed location, rather the player moves to an intercept position determined visually for the purpose of either contacting a ball, making a tackle or like athletic movement. Under such conditions, it will be appreciated that there are numerous intercept or avoidance paths available to the player. For example, a faster athlete can oftentimes undertake a more aggressive path whereas a slower athlete will take a more conservative route requiring a balancing of time and direction to make the interception. Successful athletes learn, based on experience, to select the optimum movement paths based on their speed, the speed of the object to be intercepted and its path of movement. Selecting the optimum movement path to intercept or avoid is critical to success in many sports, such as a shortstop in baseball fielding a ground ball, a tennis player returning a volley, or ball carrier avoiding a tackler.
None of the foregoing approaches spatially represents the instantaneous position of the player trying to intercept or avoid a target. One system for displaying the player in a game simulation is afforded in the Mandela Virtual World System available from The Vivid Group of Toronto, Ontario, Canada. One simulation is hockey related wherein the player is displayed on a monitor superimposed over an image of a professional hockey net using a technique called chroma-keying of the type used by television weather reporters. Live action players appear on the screen and take shots at the goal which the player seeks to block. The assessment provided by the system is merely an assessment of success, either the shot is blocked or, if missed, a goal is scored. This system uses a single camera and is accordingly unable to provide quantification of distance traveled, velocities or other time-vector movement information, i.e. physics-based information.
Accordingly, it would be desirable to provide an assessment system in an environment representative of actual conditions for the assessment of relevant movement skills that enable the player to view changes in his actual physical position in real-time, spatially correct, constantly changing interactive relationship with a challenge or task.